Apparatus for cleaning paper stock



Feb. 23, 1932. F. c. LADD APPARATUS FOR CLEANING PAPER STOCK Filed March11, 1950 IMVENTOR. 5442 C? Lad Wk ATTORNEYS.

Patented Feb. 235, 1932 BEE STATES eann PATENT QFFECE FRANK G. LADD, 0FDALTON, MASSACHUSETTS, ASSIGNOR OF ONE-HALF TO FRANKLIN Gr. NEAL, O1"SPRINGFIELD; MASSACHUSETTS APPARATUS FOR CLEANING PAPER STOCKApplication filed. March 11, 1930.

This invention relates to a method and apparatus for cleaning pulp. Itis useful primarily in cleaning pulp just before the latter is fed ontothe wire of a Fourdrinier paper making machine. In such machines it iscommon to provide sand traps for pulp cleaningpurposes. My inventionprovides an improved pulp cleaner to use in place of the common sandtraps.

The common sand trap is a shallow trough over which the pulp (suspendedin water) flows and the impurities like sand settle to the bottom. Toaid this settling, rifiie bars extend across the trough at shortintervals to stop the current near the floor of the trough. Such sandtraps oifer various objections. They need to be cleaned frequently andthis causes trouble and expense. The attempt to trap the sand andimpurities is partially defeated by the nature of the stagnant poolsbetween the rifHe bars, and the pulp is not always cleaned as well as itcan be.

According to my invention I provide a movable floor in a cleaningtrough. upon which the impurities are caused to settle.

This floor can be moved out of the trough, cleaned, and put back inplace without necessarily interrupting the flow of pulp through thetrough or stopping the continued functioning of the cleaner.

The preferred means for this purpose is a moving conveyer belt. Thesurface of the belt is arranged to serve the bottom of the trough as itssettling floor. The belt is preferably moved oppositely to the flow ofpulp. As the sediment gradually settles on the moving floor it iscarried out of the trough to a station where it can be washed from themovable iioor and the clean floor returned to the bottom of the trough,all in one continuous movement. The large advantage in this means is, Tbelieve, in the nature of the cleaning method. This method permits thedesired sedimentation without any accumulation of the sediment to buildup a stagnant condition in the pulp cleaner. The method also permits thesediment to be removed from the pulp cleaner in such a manner as toavoid its being stirred up again after it has been Serial No. 43 .5897.

once deposited on the cleaner floor. Of course the continuity of thecleaning operation is important and desirable, butl wish to point outthat the manner in which the pulp cleaner is kept in condition for itsprimary function is more important.

Another important feature of my invention is in providing a special formof pulp cleaning belt as an element in the improved cleaner. Theconveyer belt, according to this feature, is preferably made of felt.According to another feature the felt belt has a long nap. This belt canbe made endless and of considerable thickness like felt belts now usedat other places in paper machines, but the nap is made preferably (butnot neces sarily) longer. I prefer to use such a belt for the movablefloor of the pulp cleaner. The nap will act to gather the sediment fromthe pulp and hold it throughout the slow travel of the belt from one endof the trough to the other. I feel that such a nap on the belt will'ather sediment from the pulp which would otherwise not settle butremain as free dirt in the flow of pulp to the machine.

There are other features of the invention which will be brought out inconnection with the accompanying drawings, detailed description, andannexed claims.

In the drawings Fig. 1 is a longitudinal section of the new pulp cleanerin the preferred form and in sufficient detail to make the operationclear;

Fig. 1-A is a modification of the location of the wringer rolls in Fig.1;

Fig. 2 is a plan view of Fig. 1; and

Fig. 3 is an end view.

To save drawing space in Figs. 1 and 2 a part of the middle section ofthe cleaner is broken away and that part merely indicated by dottedlines.

The cleaning trough 1 as a container may be substantially like thetrough of the ordinary sand trap. Pulp inlet 2 at one end and outlet 3at the opposite end are of the usual arrangement.

The endless belt 4 is guided on suitable pulleys 5 for a portion to liealong the bottom of the trough from one end to the other and serve asthe floor of the trough 1 so far as any deposition of sediment isconcerned. As the belt is led out of the trough at the feed end, itpasses between two wringer rolls 6 and 7, one of which may be thedriving pulley for the belt. The belt then travels over its pulleys to acleaning station where a whipper device 8 beats the sediment loose andspray devices 9 shower water on and through the felt belt to carry allsediment to the under lying collecting hopper 10. The sides of thishopper are washed from spray pipes ll. The collecting surface of thebelt is of course facing downwardly in its travel over the collectinghopper. So sediment falls off, is knocked off, and is washed off, toclean the belt surface before it returns to the trough. Just before thecleaned surface reenters the trough I provide a device 12 comprising aroll with a combing surface as indicated to pick up and loosen the nap.The belt surface thus starts its travel along the bottom of the troughin clean condition and with its nap all furred up to collect allpossible sediment and dirt from the bottom zone of the pulp flow throughthe trough.

In the operation of cleaning the pulp by my apparatus a substantialamount of fiber may be carried out of the trough by the belt. That is tothere may be a small percentage with each turn of the belt and in thelong run the amount may become substantial. For this reason I provide anauxiliary cleaner 13 into which the collecting hopper 1O guides all thedirt and wild fiber. This cleaner may be of a usual type such as areprovided with an agitated screen or series of screens to separate thecoarse particles from the fine pulp. ii suiiicient separation isobtained so that the fiber can be reclaimed by pumping it back to theinlet end of the pulp cleaning device above to again pass into thetrough. I have not shown the detail of the auxiliary cleaner as thesestructures are known. Only the dirt outlet 14 and the reclaimed pulpfiber outlet 15 from this cleaner need be considered in understanding myarrangement. The latter outlet is shown leading to a pump 16 and to theinlet supply 17 for the primary cleaner.

In the trough 1, I prefer to provide cross slats l8. These are arrangedsomewhat like the rilile bars in the ordinary sand trap except that theydo not rest on the floor of the trough. In my trough they are preferablysp ced far enough above the floor to avoid scraping the belt and yet notfar enough to provide for any substantial flow of pulp under theirbottom edges. I also preferably incline them against the pulp flowinstead of oppositely as in the case of rifile bars generally. Theseslats 18 may be mounted for ready adjustment both with respect to theirinclination and their distance above the trough floor. Their object isto control the pulp flow so as to help bring about the desired depositof sediment on the floor of the trough. By my arrangement, however,perfectly dead or stagnant corners and pockets are avoided in the flowand yet the possible circulation is slow enough to help the dirt tosettle.

The travel of my belt along the bottom of the trough may be so slow asto avoid any appreciable effect in the movement of the pulp. Themovement of the latter from the inlet to the outlet of the trough maytake place in substantially the same way as if the floor of the troughwere stationary. The deposit of the sand and sediment can take place inthe same way as if the floor were stationary, except that by effectingthe removal and cleansing of the fioor the sedimentation is carried onbetter because there is no accumulation of dirt to gradually saturatethe region where sedimentation should take place.

In my above description of the operation I have confined the plan to anoperation somewhat parallel. to the sand trap operation of simpledeposition on the floor of the trough. The invention is good for thatpurpose, but other advantageous operations are feasible and sometimes ofadvantage. By moving the belt faster I can bring the nap of the feltinto more effective operation for combing the bottom strata of the pulpflow. This would be of advantage in some cases. By ready adjustment ofthe belt speed I can accommodate the cleaner to the kind of pulp(meaning also the amount and/or kind of foreign matter to be removed)bein cleaned, or to various modes of operation on the same pulp to getthe best results. Where the belt has its speed increased the amount ofpulp taken out with the dirt tends to increase, but with my auxiliarycleaner arranged to auto matically return this pulp to the trough, thatdifliculty is nicely overcome.

It may be desirable in some cases to provide a trough to take away thewater squeezed out of the belt by the wringer rolls instead of returningit to the trough. This water may be too dirty to return, in which caseit can be diverted to the collecting hopper. I have shown this slightmodification at Fig. 1-A.

Many other modifications and variations in the different details of myinvention, both in structure and mode of operation, may he made withoutdeparting from its character istics now to be pointed out in thefOllOWlILl' claims.

lVhat I claim is:

1. A cleaning apparatus for pulp and the like comprising a containerprovided with spaced inlet an d outlet between which a flow can bemaintained, a movable sediment collecting floor having excess surfacefor the container. and means to maintain said floor between the inletand outlet upon moving it toward one end of the container and then outof the flow and toward one end of the container and into the flow.

2. A cleaning apparatus for pulp and the li re comprising a settlingtrough through which pulp may flow, a flexible member having portionsarranged to serve as the settling floor for the trough, and means tochange said portions Without interrupting the flow.

S. A cleaning apparatus for pulp and the like comprising a settlingtrough through Which the pulp may have a continuous flow, an endlessbelt and guide means to hold successive portions of the belt at thebottom of the trough to serve as a collecting floor Whereby the sedimentmay be 'ently removed from the trough before it accumulates to anobjectionable degree.

at. A cleaning apparatus for pulp and the like comprising a settlingtrough through which the pulp may have a continuous flow, an endlessbelt, guide means and driving means to pass the belt into the trough andfrom one end to the other to serve as a collecting floor and then out ofthe trough whereby the floor may be cleaned Without interrupting thepulp flow through the trough.

5. A cleaning apparatus for paper pulp comprising a continuous flowsettling trough, a movable endless belt to serve as the settling floorof the trough, driving means for the belt and also guiding meanstherefor arranged to carry one belt flight from end to end of the troughand the other flight to re turn it outside the trough, and means toclean the belt arranged adjacent the second flight.

6. A cleaning apparatus for paper pulp comprising a continuous flowsettling trough, an. endless belt of felt With a nap to assist thecleaning operation, guide and driving means for said belt arranged tocarry it in at the out let of the trough and along the bottom to serveas the settling floor for the trough and out of the trough at its inletend, and means to clean the belt in its path back to the inlet end ofthe trough.

7. A cleaning apparatus for paper pulp comprising a continuous flowsettling trough, an endless belt of felt With a nap to assist thecleaning operation, guide and driving means for said belt arranged tocarry it in at the outlet of the trough and along the bottom to serve asthe settling floor for the trough and out of the trough at its inletend, means to clean the belt in its path back to the outlet end of thetrough, and means to raise the nap on the belt after it is cleaned.

8. A cleaning apparatus for paper pulp comprising a settling trough likea sand trap, a felt floor for the trough, and means to hold said floorin position While permitting successive portions of it to be removedfrom the trough for cleaning and other portions to be inserted tomaintain the floor area Without interrupting the flow of pulp along thefloor.

9. A constant flow pulp cleaning apparatus arranged to deliver cleanedpulp to a constantly running paper making machine, said apparatuscomprising a settling trough With means to regulate the pulp flow fromone end to the other, an endless belt and guide means to hold successiveportions of the belt to serve at all times as the floor of the trough,means to move said belt oppositely to the flow of pulp through thetrough and carry successive portions out of the trough for cleaning, andmeans to clean the belt.

10. A constant flow pulp cleaning appara tus arranged to deliver cleanedpulp to a constantly running paper making machine, said apparatuscomprising a settling trough With means to regulate the pulp flow fromone end to the other, an endless belt and guide means to hold successiveportions of the belt to serve at all times as the floor of the trough,means to move said belt oppositely to the flow of pulp through thetrough and carry successive portions out of the trough for cleaning,means to clean the belt, and means to regupn pulp fibers taken from thetrough by the 11. In a cleaning apparatus an endless felt belt, acleaning chamber, means to drive the belt through the chamber to collectits dirt, and means to renovate the belt outside the chamber, allarranged for continuous operation.

12. A long flow box located in the feed apparatus for a paper makingmachine, means to control the flow of pulp through said box to permitimpurities to settle, an endless belt having a surface arranged toreceive the impurities at the bottom of the box, and deliver themoutside the box Without interrupting the operation of the feedapparatus.

13. In combination for the purpose described, a flow box, a fabric beltto serve as the floor of the box, and means to take suocessive portionsof the belt outside the box, clean them and return them to the boxWithout interrupting the flow, said means including Wringer rolls, ashower device, a beater, and a nap lifter.

14. A settling apparatus for cleaning paper stock, having a passage forslow flow of the material, an endless belt With a portion serving as thefloor of said passage, cleaning means for the belt, driving means forthe belt and cleaning means, all arranged to maintain a settling floorfor the passage Without storage of sediment thereon.

15. The combination in apaper stock cleaner of a settling containerarranged for constant flow from end to end, a belt and guide means, aportion of said belt serving as the floor of the container and the restof the belt looped outside and underneath the container, and means toclean the belt in its passage along said loop.

16. The combination in a paper stock cleaner of a settling containerarranged for constant flow from end to end, a felt belt and guide meansa portion of said belt serving as the floor of the container and therest of the belt looped outside and underneath the container, Wringerrolls for said belt outside the container, a shower device and dirtloosening device adjacent the belt underneath the container and a naprenovator device adjacent the belt outside the container.

17. The method of taking dirt like sand, etc. from paper stock as itflows to the paper making machine which consists in running the stockover a portion of an endless belt long enough to permit separation ofthe dirt by sedimentation on the belt, guiding said belt out of thestock to clean the belt and re turning it in cleaned condition Withoutinterrupting the flow of stock to the machine.

In testimony whereof I have aflixed my signature.

FRANK C. LADD.

